This invention relates to mounting systems having tilt and swivel capability used in connection with equipment which must be frequently and accurately directionally repositioned. In particular, the subject matter of this invention is a mounting system for remotely controlled television surveillance systems or directional antennas such as those used in microwave transmission systems.
The demand for stable and reliable motorized mounting systems which may be remotely controlled has been increasing as the versatility and sophistication of the associated equipment increases. For example, television surveillance systems are presently used to permit observation of processes taking place in hostile environments, to allow observation of potentially dangerous areas without endangering the operator, and to expand the senses of the operator by permitting observation of events taking place at great distances. These systems are presently being used extensively in locations such as foundries, banks, and airports.
Mounting systems are presently available which permit full 360.degree. rotation, a so-called "panning" operation, and also permit the camera to be raised and lowered a full 180.degree., a so-called "tilt" operation. Unfortunately, the stability of these mounting systems has not kept pace with the increased demands being placed upon them. This problem may be illustrated by recognizing that when a camera is used to observe an event taking place at a distance of 1,000 yards, which is common in an airport setting, a camera deviation of merely 1.degree. will cause the camera focus to move approximately 50 feet. In view of these demanding conditions, a mounting system which allows no free movement of the camera and remains positioned under such varying load conditions as those caused by gusting winds, becomes a very real necessity.
Present systems generally include a rectangular base which contains the motor and drive system. The drive rotates a shaft extending through opposite sides of the base. Attached to the ends of the shaft are the depending legs of an inverted U-shaped frame upon which is mounted the device to be directionally positioned. Rotation of the shaft thus causes the camera to tilt. A similar arrangement connects the base to a support and allows the system to swivel or pan. The shafts are generally of a small diameter, approximately 1", and are attached to the drive gears by means of a key and set screw arrangement. Normal machining tolerances generally permit some free play or "backlash" between the drive gear and the shaft and frequently between the shaft and the frame legs. Backlash results in slight but undesirable motion of the camera relative to the support frame in both the tilt and pan directions causing the camera focus to deviate from the object to be viewed.
While methods are available to reduce or eliminate these backlash problems, such as welding the shaft to the support legs and drive gear or reducing manufacturing tolerances, these solutions either preclude the possibility of disassembly or increase manufacturing costs.
Axial free play between the shafts and their bearings causes the same undesirable camera motion, and it has therefore been necessary in existing systems to incorporate relatively complicated and expensive means to reduce axial movement of the shaft relative to the base.
Thus, while these systems have proven workable and adequate in the past, the rotational and axial backlash inherent in these systems can no longer be tolerated in the presently more sophisticated surveillance systems.
Considering the drawbacks present in existing mounting systems, I have developed a mounting system which eliminates relative rotational and axial movement between the camera frame and the base and between the base and the ultimate camera support, which may be manufactured and assembled by conventional methods, and which may be easily and quickly disassembled for repair or adjustment.